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# ABC COMPUTER COMPANY, LTD.
A4879
Processor 80486SX/80487SX/80486DX
Processor Speed 25/50MHz
Chip Set UMC
Max. Onboard DRAM 64MB
SRAM Cache 64/128/256KB
BIOS AMI
Dimensions 220mm x 330mm
I/O Options None
NPU Options 4167
IMG IMG 1
+------------------------------------------------------------+
| CONNECTIONS |
|------------------------------------------------------------|
| Purpose | Location | Purpose | Location |
|-------------------+----------+------------------+----------|
| Power LED & | J1 | Reset switch | J4 |
| keylock | | | |
|-------------------+----------+------------------+----------|
| Speaker | J2 | Turbo LED | J5 |
|-------------------+----------+------------------+----------|
| Turbo switch | J3 | External battery | J6 |
+------------------------------------------------------------+
+------------------------------------------------------------+
| USER CONFIGURABLE SETTINGS |
|------------------------------------------------------------|
| Function | Jumper | Position |
|--------------------------------------+---------+-----------|
| » | Monitor type select color | W18 | closed |
|---+----------------------------------+---------+-----------|
| | Monitor type select monochrome | W18 | open |
|---+----------------------------------+---------+-----------|
| » | Battery type select internal | W22 | closed |
|---+----------------------------------+---------+-----------|
| | Battery type select external | W22 | open |
+------------------------------------------------------------+
+------------------------------------------------------------+
| SRAM JUMPER CONFIGURATION |
|------------------------------------------------------------|
| Jumper | 64KB | 128KB | 256KB |
|--------+-----------------+----------------+----------------|
| W2 | pins 1 & 2 | pins 2 & 3 | pins 2 & 3 |
| | closed | closed | closed |
|--------+-----------------+----------------+----------------|
| W3 | pins 1 & 2 | pins 1 & 2 | pins 2 & 3 |
| | closed | closed | closed |
|--------+-----------------+----------------+----------------|
| W4 | open | pins 2 & 3 | pins 2 & 3 |
| | | closed | closed |
|--------+-----------------+----------------+----------------|
| W5 | pins 1 & 2 | pins 1 & 2 | pins 1 & 2 |
| | closed | closed | closed |
|--------+-----------------+----------------+----------------|
| W6 | open | closed | closed |
|--------+-----------------+----------------+----------------|
| W7 | open | open | closed |
|--------+-----------------+----------------+----------------|
| W8 | open | open | closed |
|--------+-----------------+----------------+----------------|
| W9 | open | closed | closed |
+------------------------------------------------------------+
+------------------------------------------------------------+
| SRAM CONFIGURATION |
|------------------------------------------------------------|
| Size | Cache SRAM | Location | TAG (U10) | TAG (U11) |
|-------+-------------+------------+------------+------------|
| 64KB | (8) 8K x 8 | Banks 0 & | (1) 16K x | (1) 8K x 8 |
| | | 1 | 4 | |
|-------+-------------+------------+------------+------------|
| 128KB | (4) 32K x 8 | Bank 0 | (1) 16K x | (1) 32K x |
| | | | 4 | 8 |
|-------+-------------+------------+------------+------------|
| 256KB | (8) 32K x 8 | Banks 0 & | (1) 16K x | (1) 32K x |
| | | 1 | 4 | 8 |
+------------------------------------------------------------+
+------------------------------------------------------------+
| CPU JUMPER CONFIGURATION |
|------------------------------------------------------------|
| CPU | Jumper W10 | Jumper W11 | Jumper |
| | | | W14 |
|---------+-------------+--------------------------+---------|
| 80486DX | pins 1 & 2 | pins 1 & 2 and 3 & 4 | open |
| | closed | closed | |
|---------+-------------+--------------------------+---------|
| 80487SX | pins 2 & 3 | pins 1 & 2 and 3 & 4 | closed |
| | closed | closed | |
|---------+-------------+--------------------------+---------|
| 80486SX | open | pins 2 & 3 closed | closed |
|------------------------------------------------------------|
| Note:The location of W14 is unknown. |
+------------------------------------------------------------+
+------------------------------------------------------------+
| DRAM CONFIGURATION |
|------------------------------------------------------------|
| Size | Bank 0 | Bank 1 | Bank 2 | Bank 3 | Jumpers |
| | | | | | |
| | | | | | W12,W13,W15,W16 |
|------+--------+--------+--------+--------+-----------------|
| 1MB | (4) | NONE | NONE | NONE | pins 1 & 2 |
| | 256K x | | | | closed |
| | 9 | | | | |
|------+--------+--------+--------+--------+-----------------|
| 1MB | NONE | NONE | (1) | NONE | pins 2 & 3 |
| | | | 256K x | | closed |
| | | | 36 | | |
|------+--------+--------+--------+--------+-----------------|
| 2MB | (4) | (4) | NONE | NONE | pins 1 & 2 |
| | 256K x | 256K x | | | closed |
| | 9 | 9 | | | |
|------+--------+--------+--------+--------+-----------------|
| 2MB | NONE | NONE | (1) | (1) | pins 2 & 3 |
| | | | 256K x | 256K x | closed |
| | | | 36 | 36 | |
|------+--------+--------+--------+--------+-----------------|
| 3MB | (4) | (4) | (1) | NONE | pins 1 & 2 |
| | 256K x | 256K x | 256K x | | closed |
| | 9 | 9 | 36 | | |
|------+--------+--------+--------+--------+-----------------|
| 4MB | (4) | (4) | (1) | (1) | pins 1 & 2 |
| | 256K x | 256K x | 256K x | 256K x | closed |
| | 9 | 9 | 36 | 36 | |
|------+--------+--------+--------+--------+-----------------|
| 4MB | (4) 1M | NONE | NONE | NONE | pins 1 & 2 |
| | x 9 | | | | closed |
|------+--------+--------+--------+--------+-----------------|
| 4MB | NONE | NONE | (1) 1M | NONE | pins 2 & 3 |
| | | | x 36 | | closed |
|------+--------+--------+--------+--------+-----------------|
| 5MB | (4) | (4) 1M | NONE | NONE | pins 1 & 2 |
| | 256K x | x 9 | | | closed |
| | 9 | | | | |
|------+--------+--------+--------+--------+-----------------|
| 8MB | (4) 1M | (4) 1M | NONE | NONE | pins 1 & 2 |
| | x 9 | x 9 | | | closed |
|------+--------+--------+--------+--------+-----------------|
| 8MB | NONE | NONE | (1) 1M | (1) 1M | pins 2 & 3 |
| | | | x 36 | x 36 | closed |
|------+--------+--------+--------+--------+-----------------|
| 12MB | (4) 1M | (4) 1M | (1) 1M | NONE | pins 1 & 2 |
| | x 9 | x 9 | x 36 | | closed |
|------+--------+--------+--------+--------+-----------------|
| 16MB | (4) 1M | (4) 1M | (1) 1M | (1) 1M | pins 1 & 2 |
| | x 9 | x 9 | x 36 | x 36 | closed |
|------+--------+--------+--------+--------+-----------------|
| 16MB | (4) 4M | NONE | NONE | NONE | pins 1 & 2 |
| | x 9 | | | | closed |
|------+--------+--------+--------+--------+-----------------|
| 16MB | NONE | NONE | (1) 4M | NONE | pins 2 & 3 |
| | | | x 36 | | closed |
|------+--------+--------+--------+--------+-----------------|
| 20MB | (4) 1M | (4) 4M | NONE | NONE | pins 1 & 2 |
| | x 9 | x 9 | | | closed |
|------+--------+--------+--------+--------+-----------------|
| 32MB | (4) 4M | (4) 4M | NONE | NONE | pins 1 & 2 |
| | x 9 | x 9 | | | closed |
|------+--------+--------+--------+--------+-----------------|
| 32MB | NONE | NONE | (1) 4M | (1) 4M | pins 2 & 3 |
| | | | x 36 | x 36 | closed |
|------+--------+--------+--------+--------+-----------------|
| 48MB | (4) 4M | (4) 4M | (1) 4M | NONE | pins 1 & 2 |
| | x 9 | x 9 | x 36 | | closed |
|------+--------+--------+--------+--------+-----------------|
| 64MB | (4) 4M | (4) 4M | (1) 4M | (1) 4M | pins 1 & 2 |
| | x 9 | x 9 | x 36 | x 36 | closed |
|------------------------------------------------------------|
| Note:The locations of jumpers W12, W13, W15,and W16 are |
| unknown. |
+------------------------------------------------------------+